I'm having the same issue as bob_cart except that instead of being in the same house, it's with my friend from another state. I have no idea how this happened. Though before he bought the game the other day I let him log into my steam account and play dayz for a bit. Now though he had bought it and we played together fine but we can't be in the same server and sometimes we can't be online together at all. It keeps saying "CD Key In Use". Also as bob_cart said, we are basically playing the same profile and when one of us moves, the other spawns where he was. It's very stressful.